DESCRIPTION

The
Fn radixsort
and
Fn sradixsort
functions
are implementations of radix sort.

These functions sort an
Fa nmemb
element array of pointers to byte strings, with
the initial member of which is referenced by
Fa base .
The byte strings may contain any values.
End of strings is denoted
by character which has same weight as user specified value
Fa endbyte .
Fa endbyte
has to be between 0 and 255.

Applications may specify a sort order by providing the
Fa table
argument.
If
non- NULL
Fa table
must reference an array of
UCHAR_MAX
+ 1 bytes which contains the sort
weight of each possible byte value.
The end-of-string byte must have a sort weight of 0 or 255
(for sorting in reverse order).
More than one byte may have the same sort weight.
The
Fa table
argument
is useful for applications which wish to sort different characters
equally, for example, providing a table with the same weights
for A-Z as for a-z will result in a case-insensitive sort.
If
Fa table
is NULL, the contents of the array are sorted in ascending order
according to the
ASCII
order of the byte strings they reference and
Fa endbyte
has a sorting weight of 0.

The
Fn sradixsort
function is stable, that is, if two elements compare as equal, their
order in the sorted array is unchanged.
The
Fn sradixsort
function uses additional memory sufficient to hold
Fa nmemb
pointers.

The
Fn radixsort
function is not stable, but uses no additional memory.

These functions are variants of most-significant-byte radix sorting; in
particular, see
An D.E. Knuth Ns 's
"Algorithm R"
and section 5.2.5, exercise 10.
They take linear time relative to the number of bytes in the strings.

RETURN VALUES

Rv -std radixsort

ERRORS

Bq Er EINVAL

The value of the
Fa endbyte
element of
Fa table
is not 0 or 255.

Additionally, the
Fn sradixsort
function
may fail and set
errno
for any of the errors specified for the library routine
malloc(3).